When adequately mitigated, alkali-silica reactive aggregates can be used in concrete, but testing potential mitigation measures may require significant lead time. An alternative approach, CSA A23.2-27A, “Use of Supplementary Cementing Materials for Counteracting Alkali-Silica Reaction,” incorporates long-term performance data from laboratory prisms, outdoor exposure tests, and structures. It limits maximum alkali contents of concrete and minimum dosages of supplementary cementitious materials for use with known reactive aggregates. CSA A23.2-27A was introduced in 2000 and updated in 2004 and 2009. It’s the model for the new AASHTO PP65, and it will serve as a resource for the new ASTM Subcommittee C09.50 on Risk Management for Alkali-Aggregate Reactions